05/06 I know it goes against conventional wisdom, but
it looks like the Teflon on Formica is working for the bottom
of the rocker box! At least, it is so far without the weight of
the telescope itself being added to the mass that has to be moved.

As you may have guessed from the above statement, the azimuth
motor has successfully moved the rocker box around in a circle.
A lot has happened over the past couple days working on the scope,
so I better fill you all in. Here's a picture showing where we
are right now.

This picture gives a good overall view of how I have attempted
to drive the scope in azimuth. Everything has not gone smoothly
and the bent aluminum piece in the center of the picture is a
first effort to provide some inward force to keep the threaded
rod engaged with the JB Weld gear. The motor mount is attached
to another aluminum plate that is bolted through the bottom of
the rocker box. The bottom side looks like this:

Got everything hooked up and started the first 360 degree rotation
of the rocker box. It didn't go very far! If you look at the above
image, you can see that the motor mount is slotted. This lets
me change the angle at which the rod engages the ground board.
It turns out this is a fairly fussy adjustment: too sharp and
the motor binds. Too shallow and the rod loses engagement and
slips. It was at this point that the idea of putting some pressure
against the rod with the piece of aluminum and a spring came to
me. This sort of works. I might try putting another pressure plate
between the motor and where the threaded rod engages. The binding
of the motor was pretty much eliminated by dropped the half-stepping
rate (you will have to get into Mel's software to learn how it
is configured) from 425 to 500 for MINDELAY variable.

There is one really bad sector on the gear that may end up
causing a lot of trouble. If you recall, there were a couple places
where the plywood broke away when pulling the threaded rod free
from the JB Weld. The threaded rod has a tendency to want to jump
out of engagement at this point. I think a bit more pressure against
the rod will help reduce this problem. There is also a section
of the ground board where the JB Weld gear is a bit deeper than
other places. The rod does not engage here well at all and it
will probably be necessary to take the groove sides down a bit
to help problem.

By adjusting the angle of the rod and by applying a
small amount of pressure with my fingertips, I was able to get
the rocker box to complete a 360 degree turn. One complete turn
took a bit over 3 minutes, so I'm getting az slew speeds of a
bit less than 2 degrees per second! Chris Rowland posted on the
scope-drive list a quick formula for calculating the step size.
New Step Size = Old Step Size * Angle moved / Angle reported.

To use this, you rotate the scope a full 360 degrees. Mel's
software will tell you how far it thinks it has moved. I estimated
my full step size would be somewhere in the vicinity of 6.1 arc
seconds per full step. I left the CONFIG.DAT file to the 5 arc
seconds that Mel uses as a default. Running the box around a full
rotation and doing the calculation, my full step size worked out
to 6.1445 arc sec/step - gratifyingly close to my calculation!

Now I need to do a bit of work on the depth of the groove on
the ground board to try to get a bit better engagement. I will
also add a second pressure bar to see if that helps keep the rod
engaged with the gear. Still not sure if pressure will be sufficient
to overcome the broken out part of the ground board. If worst
comes to worst, I can just point this part of the ground board
to some part of the horizon where I will not be observing and
set the computer and battery at that location. It's probably no
more than 10-15 degrees and I tend to work one area of the sky
at night. Hey, it's a rationalization, right? Once I get a dependable
motion of the rocker box, it will be time to mount the altitude
motor and start working on that project.